Optical reference
Sky-Watcher Evostar 100ED: aperture, focal length and eyepiece fit
What the Sky-Watcher Evostar 100ED measures, the magnification and true field each eyepiece produces in it, and the barrel, mount payload and camera adapter that fit.
Published specifications
Eyepiece ladder
2 pairings| Pairing | Magnification | True field |
|---|---|---|
| Tele Vue 5mm Nagler Type 6 in the Sky-Watcher Evostar 100ED | 180x | 0.46 deg |
| Celestron X-Cel LX 18mm in the Sky-Watcher Evostar 100ED | 50x | 1.2 deg |
The Evostar 100ED is a 100 mm f/9 ED doublet, a larger apochromat whose slower focal ratio gives excellent colour correction and sharp high-power planetary and double-star views. Its 900 mm focal length reaches useful magnification with mid-length eyepieces.
Because magnification is the telescope's 900 mm focal length divided by the eyepiece focal length, a 25 mm eyepiece gives 36x here and a 10 mm eyepiece gives 90x. The highest useful magnification is the published 236x, beyond which the image dims and softens without showing more detail.
The focuser takes 2 in eyepieces, so long 2 in wide-field eyepieces such as the Omni 56 mm fit as well as 1.25 in ones.